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Saturday, December 3, 2016

Q. What's wrong with my patchbay?

By Hugh Robjohns

I have a Neutrik quarter-inch jack patchbay that I'm having problems
with. The unit is only a few months old but already I seem to be
suffering from poor connections, with signals being quiet or not coming
through properly and becoming distorted. I have isolated my outboard and
tried different cables to check if the problem lies with these, and all
roads lead back to the patchbay. Are there any methods for cleaning the
contacts in patchbays or fixing them? The patchbays I had before never
had any of these problems and I was using them for over four years.

SOS Forum Post

Technical Editor Hugh Robjohns replies: It is very
unusual for a patchbay to become unreliable in such a short time. I
presume there is no obvious environmental problem such as excessive
dust, damp or smoke? Dust, damp and smoke tend to work together,
gathering on the socket contacts to form a sticky residue which acts as a
high-resistance layer, giving the kind of problems you seem to be
experiencing. It helps if you can make sure the faceplate of the
patchbay is vertical in the rack, rather than horizontal or sloping, as
this minimises the risk of dust falling into the sockets, and that the
room is kept dehumidified and well ventilated.

Another related cause is dirty (tarnished) plugs. This used to be a
real problem in professional studios using PO316 or bantam patch cords
which employed brass plugs, but tends not to be an issue with the plated
domestic quarter-inch plugs used in most home-studio rigs. Professional
studios using brass patch plugs often use a mechanical burnisher to
clean and polish the plugs, along with an aggressive cleaner for the
sockets, but the equipment is designed to be cleaned in this way. The
plated domestic plugs and sockets are often quite soft in comparison and
will wear out very quickly if treated this way, so gentle hand cleaning
with a mild metal polish or contact cleaner — Deoxit or Servisol, for
example — might help. Don't get too enthusiastic though: excessive
rubbing with an abrasive cleaner will quickly damage or even remove the
plating, making your problems a whole lot worse! A quick wipe over with
one of the gentle cleaners mentioned above every month or two should
keep everything in good order, if surface contamination is the problem.

Another likely problem, probably the most likely, in fact, is that
your patch cables are of a non-standard size. Some of the cheaper
Chinese-made moulded patch cables are fitted with locally made plugs
that are slightly undersized and don't conform to the correct
quarter-inch specifications. Consequently, they sometimes don't make
reliable contact with some types of socket. The solution here is
obvious: try patching using good-quality leads (ideally with Neutrik
jacks on the end), and see if that works any more reliably.